The invention relates to a chuck for tools such as drills and milling cutters, adapted to be manually operated to firmly clamp the tool in the chuck and to be removably mounted together with the tool on a driving shaft of a precision drilling or milling machine.
Swiss-Patent No. 288 808 shows a chuck having a one-piece elongate hollow housing and an adjusting insert disposed within the housing and in threaded engagement therewith. A key can be inserted from the rearward side into a polygonal pocket hole formed in the insert to rotate the insert and at the same time move it axially to open or close the mouth between a plurality of jaws arranged in the housing. Disadvantages of this prior art exist in that the overall length is great, the structure is complicated and therefore not easy to manufacture, the jaws rotate when the chuck is opened or closed and the chuck is not adapted for right and left rotation because it can loosen by itself.
Chucks of other types are known from U.S. Pat. Nos. 2,479,973 and 3,861,693 but they are not adapted to clamp a tool before inserting the chuck-tool-unit into a drilling machine.